1. Field of the Invention
This invention relates in general to the assembly of an air conditioning unit. More specifically, this invention relates to a tube sheet isolator used to electrically and thermally insulate an aluminum heat exchanger from a steel supporting component and used to secure various components of the air conditioning unit upon assembly.
2. Prior Art
Air conditioning units which are commonly used for light commercial applications such as hotels, dormitories and office buildings often are of a type known as packaged terminal air conditioning units. These packaged terminal air conditioners extend through the wall of the enclosure and normally have a condensing section located for discharging heat energy to the ambient sink of the atmosphere and an evaporator section located within the enclosure wherein air in the enclosure may be conditioned. These units are usually spaced on an exterior wall of the enclosure to be conditioned located in a specific subenclosure therein. These units typically have a condensing section in communication with the ambient air. Within the condensing section there is usually a condenser, a condenser fan and a compressor. Additionally, an evaporator section is provided located in communication with the air to be conditioned. The major components of the evaporator section usually include an evaporator, an evaporator fan and controls for the unit. A partition typically separates the condensing section from the evaporator section.
In many applications it is advantageous to manufacture both the evaporator and the condenser from aluminum. It is additionally advantageous to manufacture the internal components of the unit such as a condenser fan shroud, evaporator scroll and partition or other air directing components of the unit from steel. The components are normally assembled such that the air directing components such as the condenser fan shroud and the evaporator scroll are connected to the heat exchangers. The direct connection of steel to aluminum may result in a galvanic action and subsequent corrosion of the materials.
To assemble an air conditioning unit, various subassemblies are typically made and then secured to each other. The tube sheet isolator as disclosed herein side in positioning one subassembly relative to another. Both heat exchangers may be mounted on the base pan of the unit and then all of the air directing components may be slid into engagement therewith using this isolator. Additionally, the isolator may be manufactured from a thermally insulative as well as dielectric material such that galvanic action between the dissimilar metals is prevented and thermal conduction from the heat exchanger to the air directing components is reduced.